1. Field of the Invention
This invention relates to a guide roll which is suitable for use as a guide roll for a printing press, or the like.
Prior Art
A metal roll made of iron or aluminum has heretofore widely been used as a guide roll for a printing press, an offset printing roll, a guide roll for an apparatus for producing a magnetic film and a stretched film and a roll of a rotary press and a sheet-making machine. However, since a metal roll is heavy in weight and high in inertia, it does not immediately stop its rotation when emergency stop of the apparatus is needed, thereby raising problems as to scratches caused by friction between the metal roll and the product obtained and as to mounting and replacing of such a roll being troublesome.
To solve such problems, a composite roll using therein a composite material such as resin-fixed carbon fibers has come to be used. The composite roll is a reinforced composite one obtained by hardening with a resin carbon fibers having high strength and high elastic modulus, and the like, as the main components. Such rolls (blank pipes) made of reinforced composite material are disadvantageous in that not only printed matter is blurred with an ink but also the ink adhering to the printed matter cannot be wiped off so easily due to excessively high wettability of the rolls with the ink when they are used for printing or the like. Therefore, improved composite rolls have been proposed which are provided with a surface layer of a metal (e.g. chromium or nickel) on the surface of the blank pipe to improve them in anti-wettability.
Since the composite roll is light in weight and has low inertia, it is possible for the roll to be made more accurate in controlling the number of revolutions so as render it possible to decrease scratches caused by the friction between the roll and the product at the time of emergency stop. Since the composite roll is light in weight, it can easily be mounted or replaced. Furthermore, it can be reduced in diameter and thickness, and production efficiency can be improved by increasing the number of revolutions. The composite roll exhibits less dead load deflection and can be used even in portions which require high accuracy.
The composite roll provided with the surface layer as described above has somewhat satisfactory wettability with an ink. However, when the composite roll is used as a guide roll for a printing press, the ink of printed matter will adheres to the roll and blurs the subsequent printed matter. Therefore, the means for removing ink adhering to the roll during printing is indispensable, and the cost of the printing press needed is higher as a whole. A wipe-off operation of the ink adhering to the roll must be carried out whereby the printing operation becomes troublesome.